Introductory IUPAC Organic Nomenclature

Functional Groups

Here is a list of the more important functional groups arranged in decreasing priority order for a nomenclature perspective. Note that aromatic systems (arenes) should also be thought of as a functional group, but they don't fit into the priority order list shown below. 
This priority order is important in nomenclature as the higher priority group is the principle functional group and it is typically numbered such that is has the lowest number (the locant).  

You need to learn to recognise these functional groups not just for nomenclature but in order to recognise their reactions later.
In each case the fundamental functional group unit is shown, it is this that you need to be able to recognise - pay attention to the atoms involved and the bonding patterns.

All the 3D-JMOL structures can be manipulated using your computer mouse (e.g. zoom, rotate)

Functional Group	Formula	Structure
Carboxylic Acids
Acid Anhydrides
Esters
Acyl Halides
Amides
Nitriles
Aldehydes
Ketones
Alcohols
Thiols
Amines
Ethers
Sulphides
Alkenes
Alkynes
Alkyl Halides
Nitro
Alkanes

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© Dr. Ian Hunt, Department of Chemistry, University of Calgary